The announcement comes amid a flare up in the Israeli-Palestinian conflict in Gaza, civil war in Syria and an unsettled political situation in Egypt.

State Department spokeswoman Victoria Nuland said Friday "a deep conceptual gap persists in the region" on how to handle regional security and arms control.

Nuland said the U.S. would not support a conference in which any regional state would be subjected to "pressure or isolation," a reference to U.S. concerns that participants would gang up on Israel.

Iran and Arab states often say Israel's presumed nuclear arsenal poses a threat to Middle East peace and security. Israel and Western powers see Iran as the main nuclear proliferation threat. Tehran denies any atom bomb ambitions.